Posted 01/09/2011 5:06 pm
Apart from gold, the "natural" form of all metals is to look like a rock - that's one of the hazards of living on a planet with abundant water and oxygen. If you give a coin enough time, it will look like a rock again - ask anyone that's had anything to do with uncleaned ancient bronze coins. So in that sense, we as coin collectors are constantly trying to keep our coins in as "un-natural" a state as possible.
As BadThad says, lustre is caused by microscopic flow-lines in the surface of the metal. These occur whenever a piece of metal is shaped. flow lines in random directions create an even lustre; flow lines that tend to radiate out from the centre create the "cartwheel" effect. These flow lines can be obscured by oxidation/toning/tarnish, or they can be ground flat by friction with another surface (known as "wear").
As BadThad says, lustre is caused by microscopic flow-lines in the surface of the metal. These occur whenever a piece of metal is shaped. flow lines in random directions create an even lustre; flow lines that tend to radiate out from the centre create the "cartwheel" effect. These flow lines can be obscured by oxidation/toning/tarnish, or they can be ground flat by friction with another surface (known as "wear").
Don't say "infinitely" when you mean "very"; otherwise, you'll have no word left when you want to talk about something really infinite. - C. S. Lewis
